What is your own APR? . .It maybe a lot more than the advertised one, as that is there to draw in customers.
To work out your APR, on your monthly statement you should have below the transaction box, your current Purchase interest and cash advance interest. It will be some thing like:
Purchase Interest 1.897%
Cash Interest 1.976%
Add these 2 figures together to get an average, then type it into this calculator found here:
http://www.zen122856.zen.co.uk/CompoundSheet_v1.9.xls Do not use the spreadsheet on here, as it's for bank charges only. The calculator is very accurate. If you don't have your APR or % figures, call them asking what it currently is.
When you have your APR, type this into your spreadsheet on each charge. It is not uncommen for people to have an APR of 34%...
The interest they have charged you in the past, so claim it back.
Uk